This invention pertains generally to test equipment for IMPATT diode modulators and in particular to a technique for measuring, under pulsed operating conditions, the bias port impedance of an IMPATT diode.
As is known, IMPATT diodes utilized in pulsed solid state microwave sources require high power modulators designed typically to supply around two amperes of peak current to each IMPATT diode. Because of the unknown characteristics of the IMPATT diode circuit under different operating conditions, i.e. pulse width or duty cycle, current modulator designs have generally evolved through empirical methods. Thus, due to the lack of accurate bias circuit pulsed impedance data, gross characteristics of a particular type of diode are assumed and the modulator designs developed accordingly. Obviously, if the characteristics of a selected type of IMPATT diode over a frequency band of interest and under pulsed operating conditions were known, the design of the modulator would be greatly simplified.